1. Field of the Invention
The present invention relates to a spigot-and-socket joint which is secured against sliding, in particular, against pulling apart, particularly for socket pipes manufactured by a centrifugal casting method, in which joint the spigot end of one pipe can be pushed into the socket end of the other pipe, with radial play, wherein a sealing ring and a gripping ring are disposed in the joint, which gripping ring is comprised of a plurality of gripping segments mutually spaced in the circumferential direction, which gripping segments has a spherically convex exterior surface and are interconnected in the circumferential direction by a vulcanized intermediate piece (sheet or the like) comprised of rubber or the like, and which gripping segments have a toothed configuration on their radially interior surface, whereby said gripping segments press radially against the spigot end when axial tensile forces arise, said radial pressing being generated by the interaction of the spherically convex exterior surfaces with an interior surface of the pipe socket which interior surface narrows conically as the distal end of the socket is approached.
2. Description of the Prior Art
In a known spigot-and-socket joint of this type (West German Pat. No. 2,034,325), the sealing ring is connected to the gripping ring, particularly in the region of the intermediate pieces between the gripping segments, whereby a solid structural component is formed. In order to enable a relative longitudinal movement of the spigot end with respect to the unit comprising the gripping ring and sealing ring, when the spigot end is being inserted into the socket end, a rearward-facing shoulder is provided in the interior of the socket, against which shoulder the sealing ring comes to rest and which receives the axial forces which occur during said longitudinal movement, said forces being reflected in a compression of the sealing ring. In a refinement of this arrangement, a middle shoulder is provided against which the gripping ring is forced via corresponding shoulders provided on the gripping segments, so that the sealing ring, which in this case is suspended on the gripping ring, becomes more or less elongated in the axial direction. In both cases, after the spigot end is inserted into the socket end there is a relatively large distance between the spherically convex exterior surface of the gripping segments and the interior surface of the pipe socket, which latter surface narrows conically as the distal end of the socket is approached. The first time interior pressure is applied to the pipes which are now joined, the unit comprising the gripping ring and sealing ring must cover a corresponding axial distance before the gripping ring with its gripping segments arrives at its proper gripping position in which the toothed configuration comprising wedge-shaped teeth, which act in the radial direction, can grip firmly under the compressive action of the spigot end, by which firm grip of the teeth it is assured that the pipe joint will be secure from sliding. It has been found that due to the sudden axial pressure which accompanies any relative displacement of the pipes, there is a tendency for substantial withdrawal from the socket.
The object of the present invention is to overcome the above problem and provide a spigot-and-socket joint of the anti-sliding type described supra, whereby in relatively simple and reliable fashion the gripping ring with its gripping segments can be positioned problem-free with respect to the conical interior surface of the socket and the exterior surface of the spigot end.